Surface acoustic wave device and production method therefor

Abstract

A surface acoustic wave device includes a surface acoustic wave element including a plurality of electrode pads, and a mount substrate. The surface acoustic wave element is flip-chip mounted on a die-attach surface of the mount substrate by bumps made of Au. The mount substrate includes at least one resin layer including via-holes, a plurality of mount electrodes provided on the die-attach surface of the mount substrate, and via-hole conductors. The mount electrodes are bonded to the electrode pads via the bumps. The via-hole conductors are provided in the via-holes. At least one of each of the electrode pads and each of the mount electrodes includes a front layer made of Au. At least one of the via-hole conductors is located below the corresponding bump.

1 . A surface acoustic wave device comprising:
 a surface acoustic wave element including a plurality of electrode pads; and   a mount substrate including a die-attach surface on which the surface acoustic wave element is flip-chip mounted by bumps made of Au; wherein   the mount substrate includes:
 at least one resin layer including via-holes; 
 a plurality of mount electrodes provided on the die-attach surface of the mount substrate and bonded to the electrode pads by the bumps; and 
 via-hole conductors provided in the via-holes; and 
   at least one of each of the electrode pads and each of the mount electrodes includes a front layer made of Au, and at least one of the via-hole conductors is located below the bump.   
     
     
         2 . The surface acoustic wave device according to  claim 1 , wherein at least one of the via-hole conductors is located below a bonded portion between the corresponding mount electrode and the corresponding electrode pad to the bump. 
     
     
         3 . The surface acoustic wave device according to  claim 1 , wherein at least one of the via-hole conductors is aligned with the bump, the corresponding mount electrode, and the corresponding electrode pad, when viewed in a mount direction of the surface acoustic wave element on the mount substrate. 
     
     
         4 . The surface acoustic wave device according to  claim 1 , wherein the mount substrate includes a plurality of terminal electrodes provided on a surface of the mount substrate other than the die-attach surface, and a line that connects the mount electrodes and the terminal electrodes, and the via-hole conductors define a portion of the line. 
     
     
         5 . The surface acoustic wave device according to  claim 1 , wherein the resin layer is made of a resin composition containing resin, and a glass transition temperature of the resin is within a range of about 100° C. to about 300° C. 
     
     
         6 . The surface acoustic wave device according to  claim 1 , wherein the resin layer is a glass epoxy resin layer made of glass epoxy in which a glass woven cloth is impregnated with epoxy resin. 
     
     
         7 . The surface acoustic wave device according to  claim 1 , wherein the mount electrodes are made of Au, and each of the mount electrodes includes a laminated body including an Au layer that defines a front layer and a Ni layer made of Ni. 
     
     
         8 . The surface acoustic wave device according to  claim 7 , wherein the laminated body includes a plurality of plated layers containing the Ni layer, and the Ni layer has a largest thickness among the plated layers. 
     
     
         9 . The surface acoustic wave device according to  claim 1 , wherein the via-hole conductors are made of Cu. 
     
     
         10 . The surface acoustic wave device according to  claim 1 , wherein the mount substrate includes a plurality of terminal electrodes provided on a surface of the mount substrate other than the die-attach surface, and a line that connects the mount electrodes and the terminal electrodes, and the line is provided in a portion of the die-attach surface of the mount substrate other than an area opposing a piezoelectric substrate of the surface acoustic wave element. 
     
     
         11 . The surface acoustic wave device according to  claim 1 , further comprising a sealing resin layer provided on the mount substrate to seal the surface acoustic wave element. 
     
     
         12 . The surface acoustic wave device according to  claim 1 , wherein the mount substrate includes a plurality of resin layers, the via-hole conductors are provided in at least one of the resin layers and are located below the bumps and below bonded portions of the mount electrodes and the electrode pads to the bumps. 
     
     
         13 . The surface acoustic wave device according to  claim 12 , wherein the via-hole conductors are aligned with the bumps, the mount electrodes and the electrode pads when viewed in a mount direction of the surface acoustic wave element on the mount substrate. 
     
     
         14 . The surface acoustic wave device according to  claim 1 , wherein the mount substrate includes a plurality of resin layers, the via-hole conductors are provided in the plurality of resin layers and are located below the bumps and below bonded portions of the mount electrodes and the electrode pads to the bumps. 
     
     
         15 . The surface acoustic wave device according to  claim 14 , wherein the via-hole conductors are aligned with the bumps, the mount electrodes and the electrode pads when viewed in a mount direction of the surface acoustic wave element on the mount substrate. 
     
     
         16 . The surface acoustic wave device according to  claim 1 , wherein the mount substrate includes only the at least one resin layer. 
     
     
         17 . The surface acoustic wave device according to  claim 1 , wherein mount substrate includes a plurality of resin layers. 
     
     
         18 . The surface acoustic wave device according to  claim 1 , wherein the surface wave device is a Chip Size Package device. 
     
     
         19 . A production method for the surface acoustic wave device according to  claim 1 , wherein the surface acoustic wave element is flip-chip mounted on the mount substrate by applying a load to the surface acoustic wave element in a direction to bring the mount substrate and the surface acoustic wave element closer to each other and applying ultrasonic waves to the surface acoustic wave element while heating the bumps and the mount electrodes, or the bumps and the electrode pads in a state in which the bumps are in contact with the mount electrodes or the bumps are in contact with the electrode pads. 
     
     
         20 . The production method for the surface acoustic wave device according to  claim 19 , wherein the bumps and the mount electrodes, or the bumps and the electrode pads are heated to a temperature higher than or equal to a recrylstallization temperature of Au when the surface acoustic wave element is flip-chip mounted on the mount substrate.